Objectives: Gene cloning, purification, and characterization of γ-glutamyltransferase from Pseudomonas syringae (PsGGT) were performed in Escherichia coli.
Results: PsGGT was partially purified to 13-fold, with a specific activity of 0.92 U/mg. The molecule is presumed to be a heterodimeric consisting of large (37 kDa) and small (21 kDa) subunits. The optimal pH and temperature for hydrolytic activity were 8 and 37 °C, and those for transfer activity were 9 and 50 °C, respectively. PsGGT could transfer β-aspartyl moiety from asparagine to hydroxylamine and the γ-glutamyl moiety from glutamine to hydroxylamine.
Conclusion: PsGGT demonstrated novel functionality on both γ-glutamyltransferase and β-aspartyltransferase.
Keywords: Pseudomonas syringae; β-Aspartyl hydroxamate; β-Aspartyltransferase; γ-Glutamyltransferase.